The viscoelastic properties of strongly coupled Yukawa liquids are characterized by computing the complex shear viscosity $\eta \left(\omega \right)$. This is done using three methods of molecular-dynamics simulation: equilibrium, nonequilibrium, and Langevin dynamics, all with a mutually repulsive Yukawa interparticle potential. A change from viscous to elastic response is observed with increasing frequency, as well as a decrease of the magnitude of the viscosity with increasing frequency. The Langevin simulation reveals that the dependence of the complex viscosity on the friction has a different character for hot and cool liquids. At $\omega =0$, we find that as friction increases, the viscosity diminishes at high temperature but increases at low temperature. In addition to finding its frequency dependence, we also derive the wave-number (length-scale) dependence of the shear viscosity.

• Received 17 December 2009

DOI:https://doi.org/10.1103/PhysRevE.81.056404